Preparation Of Silicone Emulsions And Characterization Of Their Properties

Silicone emulsion has good interface properties of the silicone polymer, with water as a dispersion medium and it’s organic solvent-free, non-toxic, easy to use and safe, so it has been widely used. In this paper, the goal is to prepare silicone release agent with excellent performances, which will be used in metal casting manufacturing, in order to protect the mold, improve the quality of products and reduce defective rate.To prepare silicone oil micro-emulsion with storage stability, a suitable emulsifier should be selected and blended well first, and then determine the appropriate emulsification method. In this paper four nonionic surfactants and a stabilizer was used to make a nonionic composite emulsifier which is suitable to the silicone emulsion, by adopting the HLB method (hydrophilic-lipophilic balance method) and restricted mixing uniform design method. Then use a high shear homogenizer to shear and stir in the phase inversion emulsification method to prepare silicone emulsion, while make an emphatic study on the effects of the emulsifier content, emulsification time, stirring rate, emulsification temperature and pH value on the properties of silicone emulsion. Under the optimum conditions, the silicone emulsion which has small particle size、excellent performances and fine and homogeneous was prepared.In order to meet the market need of high concentration of silicone emulsions, the solid content of the emulsion was tried to be increased gradually, and then a series of different solid content emulsions were prepared, as the solid content are respectively50%,60%,65%,70%. In the process, the effects of emulsification time and stirring rate on the stability of emulsion with solid content of65%were studied. Then study the thinning properties of the high concentration of silicone emulsions, as well as the performances of the diluted emulsion, and evaluate the high concentration of silicone emulsions.In this paper the products which have excellent performances, high concentration and good thinning properties were successfully prepared, and the excellent performances are as follows:○1weather resistance stability: put the samples in the environment of60℃and-20℃for24hours, then take them out and let the temperature return to room temperature naturally, while there is not emulsion breaking or delamination phenomenon;○2sedimentation stability: samples were centrifuged at speed of6000r/min for30minutes while there is not emulsion breaking or delamination phenomenon;○3high concentration of silicone emulsions: silicone emulsion with solid content of65%can be diluted easily, and after dilution it has good weather resistance stability and sedimentation stability;○4storage stability: put silicone emulsions at room temperature for6months while there is not emulsion breaking or delamination phenomenon.